In what situation will a person be excused from the requirements of a subpoena?

A person will be excused from the requirements of a subpoena when there is a court order or another legal provision that specifically allows for such an exemption. This highlights the authority of the court in managing legal proceedings and ensuring that the legal process is followed while allowing for legitimate reasons to be excused from compliance. The legal system provides structures in which individuals can be liberated from the obligations imposed by a subpoena, thus emphasizing legal due process and protection of individuals' rights within the judicial framework.